Linear drive unit

ABSTRACT

A linear drive unit ( 1 ) possesses a first principal body ( 2 ) with a U-like section part ( 4 ) and furthermore a second principal body ( 3 ) with a drive housing ( 7 ). Using at least one drive means the two principal bodies (and  3 ) may be driven to perform a linear relative movement. The section part ( 4 ) straddles the drive housing ( 7 ), its longitudinal limbs ( 5   a  and  5   b ) being opposite to the side faces ( 13   a  and  13   b ) of the drive housing ( 7 ) with the intermediate placement of linear guide means. The section part ( 4 ) comprises two section elements ( 23   a  and  23   b ) each having one of the limbs ( 5   a  and  5   b ), such section elements being firmly joined together and being placed opposite to each other alongside each other setting the guide play of the linear drive means.

[0001] The invention relates to a linear drive unit comprising a firstprincipal body having a section part, which is U-like in cross section,a second principal body, which has a housing (drive housing), saidhousing being placed at the U-like opening of the section part with theplacement therebetween of linear guide means permitting a guided linearrelative movement, and at least one drive space in the interior of thedrive housing, such drive space containing components of a drive meansprojecting on at least one terminal side of the second principal bodyand engaging the associated axial terminal region of the first principalbody, and on activation thereof the linear relative movement is causedbetween the two principal bodies.

[0002] In the case of a linear drive unit of this type disclosed in theEuropean patent publication 0 603 459 A2 the slide-like first principalbody has its U-like section part set on the top side of the drivehousing of the second principal body straddling a guide rail mounted onthe top side of the drive housing. In the principal body two drivespaces are formed, which each house components of a fluid operated drivemeans, which are connected with the one axial terminal region of thefirst principal body. By activation of the drive means a linear relativemovement may be produced between the principle bodies, linear guidemeans placed between the two principal bodies serving to provide forguidance of the movement.

[0003] One disadvantage of the known linear drive unit resides in thefact that the guide play of the linear guide means is relativelydifficult to adjust. As a rule such adjustment is performed by resettingthe position of the components, running of the section part of the firstprincipal body, in relation to the principal body. On the one hand thismeans having suitable adjustment means, something which increases thecosts of production of the linear drive unit. On the other hand theadjustment is relatively complex, because the linear guide means arecovered over by the U-like section part of the first principal body andtherefore are only to be accessed or seen with difficulty.

[0004] One object of the present invention is to provide a linear driveunit, which despite having an economic price is simple and exact asregards adjustment.

[0005] In order to achieve this aim there is a provision such that thesection part of the first principal body straddles the drive housing ofthe second principal body so that its longitudinal limbs flank thelateral side faces of the drive housing, the linear guide means beingarranged between each limb of the section part and the facing lateralface of the drive housing, and that the section part comprises twosection elements which respectively comprise one of the limbs and arefirmly fitted together so as to set the guide play of the linear drivemeans alongside each other.

[0006] Accordingly a linear drive unit is provided, in the case of whichduring assembly of the U-like section part the guide play of the linearguide means can be simultaneously automatically set so that latercomplex adjustment work is unnecessary and it is possible to useinexpensive linear guide means, which for their part do not have anyspecial play adjustment means. The limbs, which flank the drive housing,of the U-like section part are components of originally separate sectionelements, which during assembly of the linear drive unit are placedalongside each other, so that initially they are freely movable andslidable in relation to each other and the width of the intermediatespace between their limbs may be varied and set by predeterminingdifferent relative positions. Since the set width of the intermediatespace directly influences the guide play of the linear guide meansplaced between each respective limb and the drive housing, it istherefore possible to preset the desired guide play by the selectedpositioning and biasing effect very simply. By then firmly joiningtogether the section elements, as for instance by bonding, the settingproduced will be permanently maintained so that later adjustment willnot be necessary. More particularly in the case of linear drive unitswith small and miniature dimensions the product design in accordancewith the invention exhibits unique advantages, because in this caseformerly owing to the miniaturized structure manipulations could only beperformed in an extremely awkward manner if at all.

[0007] Further advantageous developments of the invention are defined inthe dependent claims.

[0008] The linear guide means are preferably designed in the form ofrolling element guides and possess guideways provided on each limb ofthe section part and on the facing lateral faces of the drive housing,such guideways cooperating with intermediately placed rolling elements.The latter can in this case be grouped together as rolling elementunits.

[0009] The section elements constituting the section part are preferablyL-like in cross section and so put together that they overlap at pairsof their L-like limbs. In the overlap part it is possible for the L-likelimbs to be bonded together or joined together in some other fashion.

[0010] In the case of a particularly advantageous design the drivehousing is provided with two juxtaposed drive spaces for each on driveunit, the two drive units being able to engage at the same axial endregion or at two opposite end regions of the first principal body. Thelast named design is more particularly to be employed in connection witha first principal body which is long in relation to the overall lengthof the second principal body, the second principal body being overlappedat both oppositely facing terminal faces by the first principal body.

[0011] The drive units may be so designed that each of them isresponsible for the production of the linear relative movement in onlyone of the two possible directions of motion. It is particularlyadvantageous for this to be in conjunction with a design of the drivemeans in a fluid operated system, since here the number of seals issubstantially reduced.

[0012] Each respective drive means has, in the case of a fluid operateddesign, preferably a piston which is arranged in a sliding manner in anassociated working space in the drive housing, said piston engaging therespective terminal axial end region of the first principal body by wayof a force or power transmitting part, which extends longitudinally. Inthis case the power transmitting part may be annular in design and, inorder to favor simple production, constitutes a sort of plunger pistontogether with the piston.

[0013] In the case of a component unit designed in a hollow-form thereis the possibility of accommodating an abutment unit in the interior ofthe piston and/or of the force transmitting part, said unit being ableto be used to set the terminal position of the piston and accordingly ofthe relative movement produced by it. The abutment unit willconveniently have a variably positionable abutment part in order to setdifferent terminal positions of the piston as may be required.

[0014] Resetting the terminal position of the piston is preferablyperformed through an opening provided at the end of the forcetransmitting part opposite to the piston, such opening permitting theintroduction of a suitable setting tool.

[0015] The abutment unit may be provided with a buffer and/or dampingmeans in order to reduce the terminal impact.

[0016] It is convenient for the respective-drive means to engage therespective axial terminal region of the first principal body by theintermediary of a transverse part, such transverse part extending in theintermediate space between the two limbs of the section part andpreferably being anchored also on both limbs. This transverse part maymore particularly be plate-like and be so aligned that the plane of itsplate is perpendicular to the longitudinal axis of the first principalbody.

[0017] It is more especially advantageous for the transverse part to sointerlock with the two limbs that between it and the section partplay-free force transmission is possible, and at least a small degree ofplay permitting movement being present between the transverse part andthe limbs in the transverse direction, such play existing simultaneouslyon assembly of the section elements and/or on permanent fitting togetherof same. This means that there is a play-free transmission of the driveforces, there at the same time being an exact, aligned arranged of allcomponents, something which prevents excessive wear. It is possible tohave such a provision that the transverse part is floatingly mounted onthe section part athwart the latter, either by leaving a certain spacefor play or by integration of elastically yielding compensation means.

[0018] In the following the invention will be described in detail withreference to the accompanying drawings.

[0019]FIG. 1 shows a preferred embodiment of the linear drive unit inaccordance with the invention in a perspective view.

[0020]FIG. 2 shows the linear drive unit of FIG. 1 partially broken awayat one drive means.

[0021]FIG. 3 shows a longitudinal section taken through the linear driveunit in the part, which is shown partially broken away in FIG. 2, on theline III-III.

[0022]FIG. 4 is an exploded elevation-of the principal components of thelinear drive unit of FIGS. 1 through 3.

[0023] The linear drive unit 1 illustrated by way of example possessesan elongated first principal body 2 and a second principal body 3 havinga shorter overall length in comparison with the first principal body 2.

[0024] The first principal body 2 has an elongated section part 4,having a U-like cross section, with two limbs 5 a and 5 b placedopposite each other in the transverse direction and with a spacingbetween them and furthermore a rib 6 connecting them.

[0025] In the working embodiment illustrated the second principal body 3comprises a block-like, elongated housing, which will be termed a drivehousing 7 and which in the interior has two drive space 8 a and 8 bwhich are adjacent to each other and parallel, such drive spaces havinga longitudinal extent. The longitudinal extent of the drive space 8 aand 8 b is parallel to the longitudinal axis 12 of the linear drive unit1, such longitudinal axis 12 also representing the longitudinal axes ofthe two principal bodies 2 and 3.

[0026] The section part is so mounted on the second principal body 3with its U-like opening to the fore that it straddles the drive housing7 thereof, its limbs 5 a and 5 b on the longitudinal side flanking thetwo facing side faces 13 a and 13 b of the drive housing 7 with aclearance.

[0027] Between each limb 5 a and 5 b and the facing lateral face 13 aand 13 b of the drive housing 7 there are linear guide means 14 ensuringa guided linear relative movement between the two principal bodies 2 and3. The resulting possible directions of motion, which are mutuallyopposite, coincide with the alignment of the longitudinal axis 12 andare indicated by the double arrow 15.

[0028] In order for the linear drive unit to fulfill its function it isprovided with at least one and preferably at least two drive means 16 aand 16 b. Since the design of these two drive means 16 a and 16 b isidentical only one of them is illustrated in detail in the drawing.References to this drive means 16 a are simultaneously to be understoodas references to the other second drive means 16 b to the extent that ina particular case nothing is stated to the contrary.

[0029] Each of the two drive spaces 8 a and 8 b is provided with one ofthe drive means 16 a and 16 b, the latter being partially received inthe respective drive space 8 a and 8 b. It extends past one of the twoaxially aligned terminal faces 17 a and 17 b out from the drive space 8a and 8 b and engages the oppositely placed axial terminal region 18 aand 18 b of the first principal body 2. By activation of the drive means16 a and 16 b it is consequently possible for the linear relative motionto be brought about.

[0030] During use the linear drive unit 1 is stationarily fixed eitheron the first principal body or on the second principal body 2 and 3,whereas a means, or respectively a component, to be moved is secured tothe other principal body. Both principal bodies 2 and 3 do for examplehave groove-like attachment means 22, which permit connection with aholding structure or with an object to be moved.

[0031] The particular design of the linear drive unit 1 renders possibleespecially simple manufacture. During assembly of the section part 4automatic setting of the guide play of the linear guide means may takeplace in order to obtain the minimum possible play in the linear guidingaction two principal bodies 2 and 3.

[0032] In order to make this possible the U-like section part 4comprises two section elements 23 a and 23 b, each having one of thelimbs 5 a and 5 b, such section elements 23 a and 23 b being placedalongside one another longitudinally and being firmly joined together.

[0033] The putting together and joining together of the section elements23 a and 23 b is conveniently performed with the drive housing 7 and thelinear guide means 14. placed between the limbs 5 a and 5 b, which areinitially are further moved apart from one another. During assembly thelimbs 5 a and 5 b, which are initially held still further apart, aremoved toward each other in the transverse direction 9 so that thedistance between them is reduced and the linear guide means 14 are movedmore and more between the limbs 5 a and 5 b and the drive housing 7 witha biasing effect. The desired biasing effect of the linear guide means14 may consequently be set readily directly as part the fitting of thesection part 4.

[0034] The two section elements 23 a and 23 b are preferably of L-likecross section so that they may be termed angle sections, which are soplaced together that they have their first L-like limbs 24 a and 24 boverlapping in the transverse direction 9. The degree of overlap may beessentially the same as the width of the intermediate space definedbetween the two limbs 5 a and 5 b. The overlap zone defines a largejoint area 25, wherein first L-like limbs 24 a and 24 b rest against oneanother and are firmly and preferably permanently joined together,preferably by bonding.

[0035] The firm and rigid joining together of the two section elements23 a and 23 b could also be done using other suitable joining methods,as for example by welding or with the alternative or additional use ofattachment elements such as screws or rivets.

[0036] The configuration of the two section elements 23 a and 23 b issuch that the optimum setting of the guide play is obtained, before thesection elements 23 a and 23 b abut one another in the transversedirection 9. This is for instance done by providing a minimum distance33, extending along the entire length of the section part, between thetwo first L-like limbs 24 a and 24 b in the direction of overlapping,which corresponds to the transverse direction 9. The first L-like limbs24 a and 24 b accordingly do not abut on the respectively other sectionelement.

[0037] The linear guide means 14 are conveniently designed in the formof rolling element or anti-friction bearing means and in the workingexample here possess pairs of bearing rods 26 and 27 arranged on onelimb 5 a and 5 b and on the lateral face 13 a and 13 b, facing it, ofthe drive housing 7, such bearing rods 26 and 27 defining guide tracks,which cooperate with intermediately placed rolling elements 28. Thelatter may roll on the guide tracks during the relative movement of thetwo principal bodies 2 and 3 on the guide tracks. It is convenient forthe rolling elements 28 to be set in groups by cages 32 or the like asrolling element units.

[0038] In the working embodiment illustrated the drive means 16 a and 16b do not directly engage the section part 4 but a transverse part 34 aand 34 b belonging to the first principal body 2, such transverse part34 a and 34 b being fitted between the two limbs 5 a and 5 b of thesection part 4 and being also anchored to these limbs 5 a and 5 b.

[0039] The two drive means 16 a and 16 b are so installed in the workingexample that as regards the first principal body 2 they only engage itsaxial terminal regions 18 a and 18 b, the one drive means 16 a being inengagement with one axial terminal region 18 a and the other on theother axial terminal region 18 b of the first principal body 2.Accordingly the first principal body 2 is provided at both axialterminal regions 18 a and 18 b with a transverse part 34 a and 34 b,which is preferably designed like a block or plate and is insertedbetween the two limbs 5 a and 5 b with the plane of extent 8 aligned tobe perpendicular to the. longitudinal axis 12. It would be possible toterm the transverse parts 34 a and 34 b lids or covers, since theysurround the intermediate space delimited longitudinally by the limbs 5a and 5 b.

[0040] Each transverse part 34 a and 34 b has terminating faces 35facing the limbs 5 a and 5 b and aligned to be oppositely orientated, atleast one of such faces having a preferably cylindrically shaped pin 36extending away from the it. Each of such pins 36 is in the associatedlimb 5 a and 5 b provided with an aligned, complementarily shaped recess37 preferably in the form of a through opening, into which theassociated pin 36 fits without play.

[0041] Owing to the pins 36 and recesses, which are in engagement witheach other, there is an interlocking anchoring effect for the transversepart 34 a and 34 b on the section part 4 so that between the respectivetransverse part 34 a and 34 b and the section part 4 force transmissionfree of play is possible in the directions 15 of the linear relativemovement.

[0042] Furthermore the dimensions of the transverse parts 34 a and 34 bare also so selected in the transverse direction 9 that the distanceapart between the terminating faces 35 provided on same is less than thedistance apart of the inner faces of the two limbs 5 a and 5 b in theassembly region of the transverse part 34 a and 34 b. This means thatthe setting of the guide play of the linear guide means 14 is not lockedby the intermediately placed parts 34 a and 34 b. In fact, owing to thedistance difference an intermediate space 38 is set between a respectivetransverse part 34 a and 34 b and the limbs 5 a and 5 b, such differencerendering it possible for the transverse part 34 a and 34 b to maintainan exact alignment as regards the engaging drive means 16 a and 16 bduring assembly irrespectively of the relative position of the sectionelements 23 a and 23 b. It is in this manner that skew running andpremature wear are prevented. In the working embodiment illustrated thetransverse parts 34 a and 34 b are at all times mounted in a floatingmanner as regards the transverse direction 9 of the section part 4 sothat even errors in alignment occurring during linear relative motionare automatically allowed for. The intermediate space 38 in this caseensures the necessary freedom of motion. As an alternative howeverelastic means could be present as well to ensure freedom of transversemovement.

[0043] As a rule it will however be sufficient to ensure thenecessary-movement play during assembly of the first principal body 2.The transverse parts 34 a and 34 b will accordingly align themselvesautomatically and may in fact be fixed in the position arrived at bybonding or some other measure in addition.

[0044] The linear drive unit 1 could readily be fitted with electricallyactivated drive means. In the working embodiment however fluid operateddrive means 16 a and 16 b are employed, whose design will be describedin more detail in the following with reference to the one drive means 16a.

[0045] Each drive means 16 a and 16 b comprises an associated piston 42sliding in a preferably cylindrically shaped drive space 8 a and 8 b,such piston being joined by means of a force transmitting part 43 withthe associated transverse part 34 a and 34 b rigidly. In the drive space8 a and 8 b on the side opposite to the force transmitting part 43 thepiston 42, which is provided with a seal 44, delimits an actuatingchamber 45, which at the other end is closed in a sealed manner by cover46. On feeding a fluid pressure medium, more particularly compressedair, into the actuating chamber 45 of one of the two drive spaces 8 aand 8 b, and simultaneous venting of the actuating chamber 45 of theother drive space, there will be a linear relative movement of the twoprincipal bodies 2 and 3 in the one direction of motion. In the case ofa reverse action of pressure and of venting the direction of motion willbe changed. This means that each drive means 16 a and 16 b in theworking example is responsible for the production of the linear relativemovement in only one of the two possible directions 15 of movement. Thissimplifies the structure, because the seal 44 arranged on the piston 42only has to seal off one point at which a dynamic sealing function ismandatory.

[0046] The supply and removal of the pressure medium is preferablyperformed through the structural unit comprising the force transmittingpart 43 and the piston 42, that is to say starting from that axialterminal zone 18 a and 18 b, at which the force transmitting member 43is attached. The associated connection opening 47 is best located on thetransverse part 34 a and 34 b and may here be formed in one of the pins36. In the working embodiment both pins 36 are provided with aconnection opening 47 in order to have a selective connectionpossibility for pressure lines.

[0047] The above mentioned structural unit comprising the piston 42 andthe force transmitting member 43 has a tube structure so that an axiallyextending cavity 48 is produced possibly having a stepped cross section,which communicates with a terminal part 49, firmly mounted in a sealedmanner in the transverse part 34 a and 34 b, of the force transmittingpart 43 by way of one or more transverse holes 52 with the connectionopening 47. The connection with the actuating chamber 45 constitutes athrough hole 43.

[0048] The structural unit comprising the piston 42 and the forcetransmitting member 43 is preferably of unitary design and reassembles aplunger piston, the outer cross section of the force transmitting member43 being the same as that of the piston 42 so that the length section,which is moved into the drive space 8 a and 8 b, of the structural unitis supported in an optimum manner in the transverse direction.

[0049] The cavity 48 may be conveniently employed in order toaccommodate an abutment unit 54 as illustrated. It renders possible avariable setting of the terminal position of the piston 42 in the inwarddirection of movement in the working example.

[0050] The inserted cartridge-like abutment unit 54 comprises anelongated head piece 55, which has an abutment part 56 of reduceddiameter fitting through the through hole 53 and extending into theactuating chamber 45. It is axially opposite to a strike face 57 whichis conveniently provided on the opposite terminating cover 46.

[0051] A screw threaded body 58 is provided on the rear side of the headpiece 51, said rear side being opposite to the abutment part 56, suchbody 58 being screwed into a holding element 61 which is hollow from endto end and is locked for its part by a threaded connection 62 or someother firm connection in the cavity 48 of the force transmitting part 43so that it cannot be turned.

[0052] A screw driver may be inserted through the outer opening 63,facing away from the second principal body 3, in the force transmittingpart 43, into the hollow holding element 61 and the screw driver mayengage a tool socket 64 or nut provided at the adjacent end of thethreaded body 58. By turning the threaded body 58 in relation to theaxially fixed holding element 61 it is possible for the axial positionof the head piece 55 and accordingly of the abutment part 56 to bechanged in relation to the piston 42. Accordingly it is possible forthat relative position of the two principal bodies 2 and 3 to beinfluenced, at which same assume a terminal position owing to engagementof the abutment part 56 and the strike face 57.

[0053] The abutment unit 54 is in the working example preferably inaddition fitted with a damping means 65. Same is seated in the interiorof the hollow head piece 51 and in the working embodiment illustratedcontains a fluid shock absorber 66, whose fender-like plunger part inthe form of the force transmitting element 67 extends coaxially throughthe tubular abutment part 56 and projects past it a little toward thestrike face 57.

[0054] On drawing near the terminal position the force transmittingelement 67 firstly comes up against the strike face 57 so that the speedof the relative movement is reduced, before finally the abutment part 56also comes into engagement with the strike face 57 to set the position.

[0055] Instead of a damping means 65 it would also be possible to have aplain buffer means, in the case of which the force element 67 would acton a rubber-like elastic yielding buffer body.

[0056] In order to ensure a particularly flat design the drive spaces 8a and 8 b and accordingly the drive means 16 a and 16 b are arranged ina common plane, which extends in parallelism to the plane of extent ofthe connecting rib 6 of the section part 4.

[0057] In principle it would be possible for the linear drive unit 1also to have only one drive space and an associated drive means.Furthermore each drive means present could simultaneously engage bothaxial terminal regions 18 a and 18 b of the first principal body 2, aforce transmitting member then engaging the two axial ends of the piston42. In the working embodiment illustrated however the above mentionedadvantages are produced as regards the reduced number of seals inconnection with a particularly compact structure in the length directionas well.

1. A linear drive unit comprising a first principal body (2) having asection part (4), which is U-like in cross section, a second principalbody (3), which has a housing (drive housing 7), said housing beingplaced at the U-like opening of the section part (4) with the placementtherebetween of linear guide means (14) permitting a guided linearrelative movement, and at least one drive space (8 a and 8 b) in theinterior of the drive housing (7), such drive space containingcomponents of a drive means (16 a and 16 b) projecting on at least oneterminal side of the second principal body (3) and engaging theassociated axial terminal region (18 a and 18 b) of the first principalbody (2), and on the activation thereof the linear relative movement iscaused between the two principal bodies (2 and 3), characterized in thatthe section part (4) of the first principal body (2) straddles the drivehousing (7) of the second principal body (2) so that its longitudinallimbs (5 a and 5 b) flank the lateral side faces (13 a and 13 b) of thedrive housing (7), the linear guide means (14) being arranged betweeneach limb (5 a and 5 b) of the section part (4) and the facing lateralface (13 a and 13 b) of the drive housing (7), and in that the sectionpart (4) comprises two section elements (23 a and 23 b) whichrespectively comprise one of the limbs (5 a and 5 b) and are firmlyfitted together so as to set the guide play of the linear drive means(14) alongside each other.
 2. The linear drive unit as set forth inclaim 1, characterized in that the two section elements (23 a and 23 b)are firmly joined together by bonding.
 3. The linear drive unit as setforth in claim 1 or in claim 2, characterized in that the linear guidemeans (14) are designed in the form of rolling guides and possess guidetracks provided on each limb (5 a and 5 b) of the section part (4) andon the facing side faces (13 a and 13 b) of the drive housing (7). suchtracks cooperating with the intermediately placed rolling elements (28).4. The linear drive unit as set forth in any one of the claims 1 through3, characterized in that linear guide means (14) associated with arespective limb (5 a and 5 b) possess rolling elements (28) fittedtogether as rolling units.
 5. The linear drive unit as set forth in anyone of the claims 1 through 4, characterized in that the two sectionelements 23 a and 23 b) are in cross section each L-like and with amutual overlap of two first L-like limbs (24 a and 24 b) are firmlyjoined together.
 6. The linear drive unit as set forth in any one of theclaims 1 through 5, characterized in that the end faces aligned in theoverlapping zone of the first L-like limbs (24 a and 24 b) do not engagethe, respectively, other section element.
 7. The linear drive unit asset forth in any one of the claims 1 through 6, characterized in thathousing (7) contains two adjacently placed drive spaces (8 a and 8 b)for one respective drive means (16 a and 16 b), the drive spaces (8 aand 8 b) preferably being in a common plane, which runs in parallelismto the plane of extent of the connection rib (6) connecting the twolimbs (5 a and 5 b), of the section part (4).
 8. The linear drive unitas set forth in claim 7, characterized in that the two drive means (16 aand 16 b) engage on opposite axial terminal regions of the firstprincipal body (2), each drive means (16 a and 16 b) only engaging atone axial terminal region (18 a and 18 b).
 9. The linear drive unit asset forth in claim 7 or in claim 8, characterized in that each drivemeans (16 a and 16 b) is responsible for the production of the linearrelative movement in only one of the two possible directions ofmovement.
 10. The linear drive unit as set forth in any one of theclaims 1 through 9, characterized in that the at least one drive means(16 a and 16 b) is designed in the form of an electrical drive means.11. The linear drive unit as set forth in any one of the claims 1through 9, characterized in that the at least one drive means (16 a and16 b) is designed in the form of a fluid operated drive means.
 12. Thelinear drive unit as set forth in claim 11, characterized in that the atleast one drive means (16 a and 16 b) possesses a piston (42) arrangedin the associated drive space (8 a and 8 b), such piston engaging, bythe intermediary of a force transmitting part (43) having a longitudinalextent, the respective axial terminal region (18 a and 18 b) of thefirst principal body (2).
 13. The linear drive unit as set forth inclaim 13, characterized in that the piston (42) in the drive space (8 aand 8 b) delimits an actuating chamber (45) on the side facing away fromthe force transmitting part (43), such chamber being able to besubjected to an actuating fluid via the piston (42) and the forcetransmitting part in order to cause a linear relative movement betweenthe two principal bodies (2 and 3).
 14. The linear drive unit as setforth in claim 12, characterized in that the force transmitting part(43) is hollow from end to end and is more particularly tubular.
 15. Thelinear drive unit as set forth in claim 14, characterized in that thepiston (42) and the force transmitting (43) are designed in the form ofa preferably integral structural unit reassembling a plunger piston. 16.The linear drive unit as set forth in claim 14 or in claim 15,characterized in that in the piston (42) and/or in the force transmittedpart (43) an abutment unit (54) is accommodated, which on the sidefacing away from the force transmitting unit (43) has an abutment part(56) extending out of the piston (42), which part can cooperate with anoppositely placed strike face (57) on the housing in order to preset aterminal position of the piston (42).
 17. The linear drive unit as setforth in claim 16, characterized in that the abutment part (56) is ableto be set axially to set different terminal positions of the piston inrelation to the piston (42) or respectively in relation to the forcetransmitting part (43).
 18. The linear drive unit as set forth in claim17, characterized in that the force transmitting (43) has an opening(63) at its end opposite to the piston (42), such opening renderingpossible the introduction of an adjustment tool serving for positioningthe abutment part (56).
 19. The linear drive unit as set forth in anyone of the claims 16 through 18, characterized in that the abutment unit(54) contains a buffer and/or damping means (65).
 20. The linear driveunit as set forth in claim 19, characterized in that the buffer and/ordamping means (65) possesses a force transmitting means (67) extendingmore particularly concentrically through the abutment part (56).
 21. Thelinear drive unit as set forth in any one of the claims 1 through 20,characterized in that the at least one drive means (16 a and 16 b)engages a transverse part (34 a and 34 b) which extends in thetransverse direction (9) of the section part (4) between the two limbs(5 a and 5 b) of the section part (4) and is anchored on the two limbs(5 a and 5 b).
 22. The linear drive unit as set forth in claim 21,characterized in that the transverse part (34 a and 34 b) is plate-likeor block-like in design and is installed between the two limbs (5 a and5 b) of the section part (4) with a plane of extent perpendicular to thelongitudinal axis (12) of the first principal body (2).
 23. The lineardrive unit as set forth in claim 21 or in claim 22, characterized inthat the transverse part (34 a and 34 b) so interlocks with the onelimbs (5 a and 5 b) of the section part (4) that between it and thesection part (4) in the directions (15) of motion of the linear relativemovement a play-free transmission of force is possible, andsimultaneously on assembly of the section elements (23 a and 23 b)and/or after firm assembly of the same there is play for movementbetween the transverse part (34 a and 34 b) and the limbs (5 a and 5 b)in the transverse direction (9).
 24. The linear drive unit as set forthin any one of the claims 21 through 23, characterized in that thetransverse part (34 a and 34 b) is mounted for floating movement in thetransverse direction (9) of the section part (4) on the section part(4).
 25. The linear drive unit as set forth in any one of the claim 1through 24, characterized in that a second principal body (3), which isshort in comparison with the overall length of the first principal body(2) is overlapped on both mutually opposite end sides (17 a and 17 b) bythe first principal body (2), a drive means engaging both axial terminalportions (18 a and 18 b) of the first principal body (2).